I had a 78 accord I bought in 83 for $200 because it had a bad head gasket. It had 80k on it. I used K&W metallic block seal, and got another 50k on the engine before having to actually replace the head gasket. When I did, it took me 4 hours in a parking lot. I then got another 100k miles before selling it.

Just be sure to follow K&Ws directions, especially flushing the engine completely. I reccomend removing the thermostat temporarily to make it easier for the copper to travel through the system. If you know what cylinder is leaking, remove the plug from it so that the copper can penetrate the leak more easily. Also, after running the engine for the required time, be sure to remove the plugs, drain the system as much as possible (lower radiator hose a Plus), remove radiator cap, and let it dry out for a couple of days. You will have much better luck that way.

If there is water in your oil, be sure to flush, and change oil and filter.

Good luck